Investigation of the relationship between peripheral neuropathy and vascular disease of the lower limb in patients with diabetes mellitus by ultrastructural examination and quantitation of biopsy tissue and an experimental animal model. An electron microscopic study will be made of human biopsy tissue to study the innervation of arteries of the lower limb in patients with diabetes mellitus. Pathological lesions of these autonomic nerves and lesions of the vessel wall itself will examined. A quantitative ultrastructural study will also be made of the structure and innervation of vascular walls after lumbar sympathectomy in order to make a morphological evaluation of the effects of surgical sympathectomy on innervation of blood vessels and on the progression of diabetic vascular disease in the lower limb. In addition a Chinese hamster diabetic mutant will be used to study ultrastructural changes due to diabetic peripheralneuropathy and concomitant pathological changes in the walls of arteries from the lower limb. An attempt will be made to correlate data obtained from the animal model with that obtained from the study of human biopsy material.